Last week, we hosted a webinar on the Weissenberg-Rabinowitsch-Mooney Correction, also known as WRM correction. What is this correction? When you are using a viscometer to measure viscosity of a liquid, there is more than just one number that comes out. Using a viscometer, you can determine if your sample is Newtonian or non-Newtonian.
A Newtonian sample references flow behavior of a fluid that is linear in relation between shear stress and shear rate. Simply put, it refers to a sample that stays the same viscosity value even if the shear rate changes. Alternatively, non-Newtonian samples reference the flow behavior of a fluid in which viscosity is dependent on the shear rate. What that means is that it will display a non-linear relation between shear stress and shear rate.
When referencing non-Newtonian samples, the sample viscosity can increase as the shear rate increases. This is called shear thickening behavior. Separately, when the sample viscosity decreases as shear rate increases, this is called shear thinning behavior.
Why does this matter? If you know that your sample is non-Newtonian, Newtonian, shear thinning, shear thickening, you can take this information and apply it when it is in the final product form. Some examples would be, with proteins, you would want the protein solution to be non-Newtonian, shear thinning, so that when it is applied into a patient, the patient experiences as little pain as possible as the sample reduces in viscosity and still being injected into the patient.
Many viscometers on the market measure index viscosity but it is quite common that proper characterization of shear rate or absolute/true viscosity is not gathered and can potentially cause gaps in the product characterization process. With VROC® technology powered viscometers, you can gather this information including viscosity as a function of shear rate and also absolute/true viscosity.